In recent years, various mold release agents have been developed to overcome the drawbacks of conventional mold release agents such as silicone oil, mineral oils, paraffin waxes, fatty acid derivatives, glycols, talc, mica, etc. The mold release agents recently proposed include, for example, a mixture of silicone oil and phosphate containing perfluoroalkyl group with 4 to 20 carbon atoms or a salt thereof (Japanese Examined Patent Publications No. 23270/1978 and No. 23271/1978), a mixture of silicone varnish and phosphate containing perfluoro-alkyl group with 4 to 20 carbon atoms or a salt thereof (Japanese Examined Patent Publication No. 48035/1982), a mixture of silicone oil or the like and polyether compound containing perfluoroalkyl group (Japanese Examined Patent Publication No. 32513/1984), etc. These new mold release agents are preferred in that they can exhibit a good mold release ability and have a longer releasing lifetime than conventional mold release agents. Among these mold release agents, the mixture of silicone oil or the like and perfluoroalkyl group-containing polyether compound rarely affects the fabrication quality of most of molded articles of polymeric materials. However, it is now required to produce mold release agents having further improved properties in view of the tendency to make molded articles of polymeric materials having increasingly more complex shapes and larger sizes. Particularly, there is a demand for mold release compositions having enhanced film-forming property and prolonged releasing lifetime.